Method and device for producing respiratory air which is harmless to health in positive pressure nasal breathing apparatus

ABSTRACT

The invention concerns a positive pressure nasal breathing apparatus in which a processed air flow is supplied at positive pressure to the person to be treated. The apparatus comprises: a first device ( 10 ) for producing a first air flow which has a given first temperature and a first degree of relative air humidity; and a second device ( 12 ) for processing the first air flow such that a second air flow to be completely or partially supplied to the person is produced. The temperature of the second air flow is lower and its degree of relative air humidity higher than that of the first air flow.

Nasal, positive-pressure respiratory devices are used for avoidingso-called obstructive sleep apnea.

Obstructive sleep apnea describes a collapse of the respiratory passagesin the pharyngeal region that repeatedly occurs during sleep and thatleads to respiratory arrests and, when it occurs frequently, instigateslasting damage to one's health due to lack of sleep and lack of oxygen.

In the positive-pressure respiratory devices known under the name nCPAP(nasal continuous positive airway pressure), a fan creates a constantpressure that is fed into the respiratory passages via a tube and anasal mask. The positive pressure in the respiratory passages preventsthe sealing of the pharyngeal musculature and thus eliminates therespiratory arrests.

For drawing off the expirated, consumed air, a continuous stream ofexhaust air is exhausted via fine exit openings along the breathingmask. The exhaust air exit openings must be made narrow so that athrottling effect is provided and the positive pressure does notcollapse but rather only a predetermined amount of exhaust air exits.

In order to completely draw off the consumed air, the amount of exhaustair must be as large as the amount of expirated air.

A health damaging effect results from positive-pressure respiration inthat the air is warmed through the compression in the fan and that therelative humidity of the air is consequently reduced in accordance withthe laws of nature. The dry air flowing continuously as a result of thestream of exhaust air dries out the mucous membranes of the respiratorypassages and results thereby in continuous complaints (symptoms)comparable to a cold.

In order to avoid these problems, it is known to employ an airhumidifier between the fan and the breathing mask.

In the early time of nasal, positive-pressure respiration, complex,regulated respiratory air humidifiers were used for this purpose, i.e.as are used in intensive care medical treatment.

In the meantime, a home, positive-pressure respiration during sleep hasbeen shown to be a matter of life or death for tens of thousands ofsleep apnea sufferers.

For this purpose, the complex, respiratory air humidifiers of intensivecare medical treatment are too complicated and too expensive.

It thus became known to use so-called cold air humidifiers, wherein theair stream coming from the fan flows through a closed housing in whichwater is bubbled by means of a pump.

Since, however, it was shown during their use that the drying out of themucous membranes in the respiratory passages could not be sufficientlyavoided using the cold air humidifiers, so-called warm air humidifiersare primarily used at the present time, as is described in theinstruction manual for PRIESS med. Technik's “Sullivan Atemgasanfeuchter(respiratory gas humidifier) Model HC 100,” said firm residing atKarstrasse 17a, 41068 Mönchengladbach, Germany.

In FIG. 1 of the drawings, this prior art is illustrated schematically.

The fan 1 creates an air stream with a positive pressure of approx. 3 to18 mbars, whereby the air stream heats up by approx. 1 to 2° C. over theambient temperature. The air stream is fed via a tube 4 from the fan 1to the air humidifier 5 and is further led from there, again via a tube6, to the nose mask 7 and the fine exit openings 8 for the exhaust airstream 9, In the evaporation container 2 of the air humidifier, thewater filled thereinto is evaporated by an electric heater 3. The airstream flowing therethrough accepts this water vapor in the evaporationcontainer 2 and is thus simultaneously warmed by approx. 4 to 60° C.over the ambient temperature.

With such warm air humidifiers, a sufficient humidification of therespiratory air is achieved to avoid the drying out of the mucousmembranes.

The warm humidification of the respiratory air, however, creates thefollowing serious problems:

Through the warm humidification, the air that had already been warmed bythe fan is warmed even more. The inhalation of this warm and humid airresults in subjective respiratory distress and results thus in frequentsleep interruption and subsequently in significant problems in fallingasleep.

Since the temperature of the warm, humidified air is higher than theambient room temperature when it exits the humidifying container,condensation forms in the respiratory tube 6 and in the nose mask 7. Inorder to avoid the formation of (bacterial) cultures (colonies) that aredangerous to one's health as a result of this humidity, the tube 6 mustbe thoroughly washed and dried daily.

A serious problem results furthermore along the fine exit openings 8 forthe exhaust air 9. Since the exhaust air 9 expands when it exits and, asa result, cools down adiabatically, further condensation from thehumidity-saturated air forms in the fine exit air openings 8 andpartially blocks these. As a result, the expirated air is no longersufficiently exhausted. The result is sleep and health disorders due tolack of oxygen.

Regarding the prior art, further reference is made to DE-C-6 34 919,which relates to a breathing chamber with cooled air, and to WO-A-9 320874, which relates to an apparatus for destroying microorganisms.

The object of the invention is to provide an apparatus for creatingrespiratory air for home positive pressure—CPAP (Continuous positivepressure) respiration of persons with obstructive sleep apnea syndromesuch that the occurrence of condensation is avoided during the creationof medically sound air humidity of the respiratory air.

For solving this problem, the features cited in claim 1 are provided.Preferred embodiments of the invention can be found in the dependentclaims.

Before going into further advantages of the invention, it will be notedin regard to the aforementioned prior art that an air stream underpositive pressure is created by the apparatus in accordance with theinvention that is subjected to treatment prior to its introduction tothe nose mask and the exit openings, said treatment being a humidifyingtreatment in the case of the prior art.

The sufficient air humidity is achieved by simple means without havingto accept the deficiencies of the known positive-pressure respirationdevices: the increased temperature of the respiratory air; the danger ofthe formation of health-threatening bacteria and lack of oxygen due tothe blockage of the air exit openings through condensation.

The relative air humidity is known to be determined by the airtemperature for invariant, absolute air humidity. This law of natureresults in the damaging reduction of the relative air humidity throughthe warming by approx. 1 to 20° C. during the creation of the positivepressure in the fan of the positive-pressure respiratory device.

If the air supplied by the fan is now cooled with suitable means byapprox. 5° C., the relative air humidity is then higher than prior tothe compression. Since the temperature of the cooled air is then approx.3° C. lower than the ambient temperature, condensation does not form ineither the breathing tube or in the exhaust air slits of the nose maskdue to the high relative air humidity.

The air tube must not longer be washed out and dried daily. Theexhausting of the consumed respiratory air is not hindered bycondensation in the exhaust air openings. The lack of oxygen as a resultof insufficient drawing off of the exhaust air is thus avoided.

The cooled respiratory air gives the subjective impression of beingfresh and allows a restful sleep.

Furthermore, the cooled air stream in accordance with the inventiondraws less humidity from the mucous membranes in accordance with thelaws of nature than an air stream of the same relative air humidity buthigher temperature of the known methods.

The cooling of the respiratory air is carried out in accordance with theinvention via a heat exchanger, whereby the air stream supplied by thefan flows through a cooling profile or section (heat sink) in a closedhousing.

The amount of heat that is to be drawn off from the air stream of max.30 liters per minute is only 3.25 W when the temperature is reduced by5° C. and can, in accordance with the invention, be drawn off usingtypical commercial Peltier elements.

The cold side of the Peltier element is thermally connected to the innercooling profile (heat sink) of the heat exchanger. The heat from the hotside of the Peltier element can drawn off to the ambient air by means ofan aired, outer cooling profile (heat sink).

Starting from the prior art of FIG. 1, an embodiment of the invention isdescribed in more detail below based on FIGS. 2-4 of the drawings. Theseshow:

FIG. 1: the prior art

FIG. 2: the schematic construction of a nasal, positive-pressurerespiratory apparatus

FIG. 3: the schematic construction of the heat exchanger and

FIG. 4: a view in the direction of A in FIG. 3.

In accordance with FIG. 2, an air stream in created by the fan 10 with apositive pressure between 3 and 18 mbars depending on the settings andled via the tube 11 to the heat exchanger 12. Through the compression,the air stream is heated between 1 to 2° C. relative to the ambienttemperature depending on the positive pressure, and the relativehumidity is thus reduced in accordance with the laws of nature relativeto its condition when sucked in. The air stream is cooled in the heatexchanger 12 by approx. 3° C. below the ambient temperature. Thus, therelative air humidity of the air stream is increased by approx. 20%relative to its condition when sucked in. The air stream is led via thetube 13 to the nose mask 14 and the fine exit openings 15 for theexhaust air stream 16. Due to the higher ambient temperature,condensation from the air stream does not form in the tube 13 or in thefine exit openings 15. The fine exit openings 15 for the exhaust airstream 16 remain free such that the respiratory air is rich in oxygenand pleasing due to its being cooled.

The heat exchanger 12 in accordance with FIG. 3 and 4 consistsessentially of a Peltier element 20 whose cold side 21 is thermallyconnected to the cooling profiles (heat sinks) 22 and 25 made of metalof higher thermal conductivity, for example aluminium, and whose hotside 23 is connected with a further cooling profile (heat sink) 24 madeof metal of higher thermal conductivity.

Via the cooling profile 24, the air stream heat electrically pumped viathe Peltier element 20 from the cold side 21 to the hot side 23 and theelectrical power loss of the Peltier element 20 is drawn off to theambient air.

The two E-formed cooling profiles 22 and 25 thermally connected with thecold side 21 of the Peltier element 20 form a meandering cooling channel26 between the air entrance 27 and the air exit 28 for the air streamsupplied by the fan 10.

The air entrance 27 and the air exit 28 of the housing 29 is formedpipe-shaped for connecting the tubes. The air entrance 27 is located atthe position of the cooling channel farthest away from the Peltierelement 20, and the exit 28 at the location closest to the Peltierelement. Thus, a nearly constant temperature gradient to the coolingprofiles 22 and 25 results for the continuous cooling of the air streamin the meandering cooling channel 26, and thus a particularly favorablecooling effect of the heat exchanger results.

Naturally, other embodiments (shapes) for the cooling profiles arepossible. In particular, the profiles could be enlarged through furtherribs for enlarging the cooling area.

In summary, one can say that the invention relates to a nasal,positive-pressure respiration device in which a treated air streamcomprising a positive pressure is fed to the person to be treated,whereby a first apparatus 10 serves to create a first air stream thatcomprises a predetermined first temperature and a first relative airhumidity, and whereby a second apparatus 12 processes the first airstream such that a second air stream is created that is entirely orpartially fed to the person, the temperature of which air stream islower and whose relative air humidity is higher than that of the firstair stream.

Preferably, the first apparatus is a fan 10 that warms the sucked-inambient air such that the first air stream possesses the predeterminedfirst temperature. The second apparatus is preferably a heat exchangerthat preferably works according to the Peltier principle.

In accordance with a further embodiment, the second apparatus is asingle Peltier element that is preferably formed on the basis of asemiconductor and that possesses a flat form of approx. 4×4 cm length aswell as a thickness of 5 to 6 mm. The nasal, positive-pressurerespiratory device also preferably provides for the ambient air warmedvia the air stream creating apparatus, i.e. the fan 10, by approx. 1 to2° C. to be cooled by approx. 3 to 6° C., preferably 5° C., via thePeltier element such that the second air stream exiting from the Peltierelement is 2 to 4° C., preferably approx. 3° C., colder than the airsucked in from the surroundings, wherein the relative air humidity ofthe second air stream exiting from the Peltier element lies approx. 30to 40% higher than the relative air humidity of the air sucked in,wherein the second air stream exiting from the Peltier element is warmedalong the path to the breathing mask, if at all, and thus possesses asomewhat reduced relative humidity, whereby however no condensation isformed, such that the exit openings 8 or slits for the exhaust airpresent behind a breathing mask supplied totally or partially by thesecond air stream are also not blocked since no condensation is formed.

Preferably, the Peltier element 20 is connected on its hot side 23 withthe cooling profile 24, and the cold side 21 comprises cooling profilessuch that the cooling channel 26 for the flowing through of air isformed. The cooling channel 26 is, as stated, preferably has ameandering shape and is formed through two intermeshed cooling profiles22, 25.

The nasal, positive-pressure respiratory device using a heat exchanger,in particular a Peltier element, comprises, in accordance with theinvention, an apparatus 10 that creates the positive pressure of therespiratory air, said apparatus 10 being in connection via tubeconnections 11, 13 with a mask 14 that comprises fine exit openings 15for the exhaust air stream, wherein a heat exchanger is introduced inthe connection between the apparatus 10 creating the positive pressureand the mask 14.

It is also possible to provide a nasal, positive-pressure respiratorydevice using a heat exchanger, in particular a Peltier element, suchthat an apparatus 10 creating the positive pressure of the respiratoryair is provided that is connected via tube connections 11, 13 with amask 14 that comprises fine exit openings 15 for the exhaust air stream,and wherein the Peltier element is located in front of the apparatus 10for creating a positive pressure. Furthermore, the nasal,positive-pressure respiratory device using a heat exchanger, inparticular a Peltier element, can be formed such that a Peltier isconnected in circuit prior to and a further Peltier element is connectedin circuit subsequent to the apparatus 10 creating the positive pressureof the respiratory air that is connected via tube connection 11, 13 withthe mask 14 that comprises fine exit openings 15 for the exhaust airstream.

I claim:
 1. A CPAP (Continuous Positive Air Pressure) respiratoryapparatus for home positive pressure respiration of persons withobstructive sleep apnea syndrome comprising a fan for creating thepositive pressure and a heat exchanger including a Peltier elementhaving a hot side and a cold side, the heat exchanger being insertedinto the air stream of the fan, said heat exchanger cooling the airstream supplied by the fan to a temperature 2-4 degrees Celcius belowambient temperature before it is supplied to a nose mask and exitopenings; the heat exchanger further comprising first and second coolingprofiles with the Peltier element being connected to the first coolingprofile and the hot side being connected to the second cooling profile.2. The CPAP (Continuous Positive Air Pressure) respiratory apparatus ofclaim 1 characterized in that the first cooling profiles have an “E”shape and form a meandering cooling channel for the air stream suppliedby the fan between an air entrance and an air exit.
 3. The CPAP(Continuous Positive Air Pressure) respiratory apparatus of claim 1characterized in that the supplied air stream is cooled by 2 to 4° C.below the ambient temperature.
 4. The CPAP (Continuous Positive AirPressure) respiratory apparatus of claim 3 characterized in that thesupplied air stream is cooled by 3° C. below the ambient temperature. 5.The CPAP (Continuous Positive Air Pressure) respiratory apparatus ofclaim 1 characterized in that the supplied air stream is cooled by 3degrees Celcius below ambient temperature.
 6. In a method for CPAP(Continuous Positive Air Pressure) for home positive pressurerespiration of persons with obstructive sleep apnea syndrome, theimprovement comprising: providing a fan and generating a positivepressure air stream from the fan and providing a nose mask having exitopenings and operatively connecting the nose mask to the positivepressure air stream; providing a heat exchanger and inserting the heatexchanger into the positive pressure air stream; conveying the airstream from the heat exchanger through a breathing tube to the nose maskand exit openings therein, cooling the positive pressure air stream withthe heat exchanger to a temperature minus 2-4 degrees Celcius belowambient temperature thereby increasing the relative humidity of the airstream; supplying the cooled positive pressure air stream to the nosemask and exit openings for maintaining the respiratory air rich inoxygen; maintaining the exit openings open by avoiding any formation ofcondensation from the cooled positive pressure air stream in thebreathing tube and in the exit openings; and facilitating an exhaust ofexhaled air through the exit openings.
 7. The method of claim 6including providing cooling in the heat exchanger by a Peltier element.8. The method of claim 7 including providing the heat exchanger withfirst and second cooling profiles.
 9. The method of claim 8 includingconnecting the first cooling profile of the heat exchanger to a coldside of the Peltier element and connecting the second profile of theheat exchanger with a hot side of the Peltier element.
 10. The method ofclaim 9 wherein the first cooling profile has an E-shape and forms ameandering cooling channel for the air stream supplied by the fanbetween an air entrance and an air exit.
 11. The method of claim 6including cooling the air stream to a temperature of 3° C. below theambient temperature.